Causes of Mouth Ulcers or Sores

Canker Sores. The main cause of 1 or 2 mouth ulcers after age 5.

Hand-Foot-Mouth Disease. The most common cause of multiple ulcers in the mouth. These ulcers are mainly on the tongue and sides of the mouth. Most children also have small deep blisters on the palms and soles. Due to the Coxsackie virus. It is common between ages 1 to 5 years.

Herpes Simplex Virus (Cold sore virus). The first infection can be severe. It can cause 10 or more ulcers on the gums, tongue and lips. Key findings are additional ulcers on the outer lips or skin around the mouth. Also, fever and difficulty swallowing. Usually occurs age 1 to 3. It usually follows contact with an adult who has active cold sores (fever blisters). Often they have kissed the child.

Cold Sores (Fever Blisters). Sores are only found outside the mouth on the outer lip. They recur 2 or 3 times a year in the same place. There are no ulcers inside the mouth. Adult cold sores are the cause of Herpes Simplex infections in young children. Occurs in 20% of teens and adults.

Mouth Injury. Common mouth injuries are biting the tongue or inside of the cheek. Others can be caused by a toothbrush. The lining of the mouth always looks white when it heals. So forgotten injuries can look like a canker sore.

Mouth Burns. Hot foods (such as pizza) can cause mouth sores. They also turn white as they heal.

Causes of Canker Sores

Canker sores have many causes.

Minor injuries to the mouth can trigger a canker sore. Examples are from a rough food or a hard toothbrush. Biting oneself while chewing can start one.

Food allergies or irritants may also be a trigger.

Vitamin deficiencies can also be a cause. A vitamin deficiency can occur if your child is a picky eater.

Canker sores can run in families (genetic).

Often, the cause is unknown.

Symptoms of Canker Sores

Small ulcers have a white center with a red border around them

Size is usually less than ¼ inch (6 mm)

Found on the inner lips and inner cheeks

The sores are very painful, even when not eating

Usually get 1 canker sore at a time. Sometimes get 2 or 3.

No fever or other symptoms

When to Call for Mouth Ulcers

When to Call for Mouth Ulcers

Call 911 Now

Not moving or too weak to stand

You think your child has a life-threatening emergency

Call Doctor or Seek Care Now

Chemical in the mouth could have caused ulcers

Dehydration suspected. No urine in more than 8 hours, dark urine, very dry mouth and no tears.

Your child looks or acts very sick

You think your child needs to be seen, and the problem is urgent

Call Doctor Within 24 Hours

4 or more ulcers

Bloody crusts on the lips

Red, swollen and tender gums

Ulcers and sores also on the outer lip

One ulcer on the gum near a tooth with a toothache

Fever or swollen face

Large lymph node under the jaw

Began after starting a medicine

You think your child needs to be seen, but the problem is not urgent

Call Doctor During Office Hours

Cold sores suspected

Mouth ulcers last more than 2 weeks

You have other questions or concerns

Self Care at Home

Canker sores suspected

Call 911 Now

Not moving or too weak to stand

You think your child has a life-threatening emergency

Call Doctor or Seek Care Now

Chemical in the mouth could have caused ulcers

Dehydration suspected. No urine in more than 8 hours, dark urine, very dry mouth and no tears.